Device to minimize the buoyancy driven flows in vertically oriented headers

Abstract

A device for minimizing a buoyancy driven convective flow inside a manifold of a fuel cell stack includes a plurality of spaced apart baffle walls. The spaced apart baffle walls are configured to be disposed inside the manifold of the fuel cell stack. The spaced apart baffle walls increase a viscous resistance to the buoyancy driven convective flow inside the manifold.

Description

FIELD OF THE INVENTION[0001]The present disclosure relates to a fuel cell stack and, more particularly, to an insert device disposed in a header of the fuel cell stack.BACKGROUND OF THE INVENTION[0002]A fuel cell has been proposed as a clean, efficient and environmentally responsible power source for electric vehicles and various other applications. In particular, the fuel cell has been identified as a potential alternative to the traditional internal-combustion engine used in modern vehicles.[0003]One type of fuel cell is known as a proton exchange membrane (PEM) fuel cell. The PEM fuel cell typically includes three basic components: a cathode, an anode, and an electrolyte membrane. The cathode and anode typically include a finely divided catalyst, such as platinum, supported on carbon particles and mixed with an ionomer. The electrolyte membrane is sandwiched between the cathode and the anode to form a membrane electrode assembly (MEA). The MEA is often disposed between porous dif...

AI Technical Summary

Benefits of technology

[0007]In concordance with the instant disclosure, a device to minimize water accumulation at a dry end of the fuel cell stack transported by buoyancy driven convective flows inside the manifold of the fuel cell stack, reduce a risk of reactant tunnel blockage due to ice formation during a shut-down of the fuel cell stack under freezing ambient conditions, and minimize related issues during a start-up of the fuel cell stack, is surprisingly discovered.

[0008]In a first embodiment, a device for minimizing a buoyancy driven convective flow inside a manifold of a fuel cell stack includes a plurality of spaced apart baffle walls. The spaced apart baffle walls are configured to be disposed inside the manifold of the fuel cell stack. The spaced apart baffle walls are in direct fluid communication with the fuel cells and have a surface area sufficient to increase a viscous resistance to the buoyancy driven convective flow.

[0009]In another embodiment, a fuel cell stack includes a plurality of fuel cells disposed in a stack, and a manifold for one of delivering a fluid to the fuel cells and exhausting a fluid from the fuel cells. A device for minimizing buoyancy driven convective flow is disposed inside the manifold. The device includes a plurality of spaced apart baffle walls disposed inside the manifold of the fuel cell stack. The spaced apart baffle walls are in direct fluid communication with the fuel cells and have a surface area sufficient to increase a viscous resistance to the buoyancy driven convective flow.

[0010]In a further embodiment, a fuel cell stack includes a plurality of fuel cells disposed in a stack between a dry end unit and a wet end unit. The fuel cell stack also includes a manifold for exhausting a reactant and water from the fuel cells. The wet end has an exhaust aperture formed therein. The exhaust aperture is in communication with the manifold. A device for minimizing buoyancy driven convective flow includes a plurality of spaced apart baffle walls disposed inside the manifold of the fuel cell stack. The spaced apart baffle walls increase a viscous resistance to the buoyancy driven convective flow. The spaced apart baffle walls extend approximately half the distance between the dry end unit and the wet end unit. The spaced apart baffle walls are oriented substantially parallel with a direction of flow of the reactant and water from the fuel cells in order to minimize an affect on volumetric flow and / or flow resistance between the fuel cells and the exhaust aperture during an operation of the fuel cell stack.

Problems solved by technology

A collection of water at the cooler dry end of the known fuel cell stack 2 can lead to ice formation and blockage of fluid ports of the fuel cells 4 under freezing ambient conditions, and related issues during a start-up of the known fuel cell stack 2.

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